New solar panels unveiled last week at a real estate developer's Laurel headquarters come with an unusual twist — an energy storage system, the first such commercial setup in the state and one of the first in the country.

That drew a crowd. But regular solar-energy projects? Not so much.

"You don't see many solar dedications now, and it's for a good reason: It's because solar is becoming more mainstream," said Thomas Leyden, CEO of Philadelphia-based Solar Grid Storage, which worked on the Laurel project. "It's run of the mill now."

That's true in an increasing number of states, including Maryland, the country's eighth-largest solar-installation market last year. And it's not just about panels on government roofs or environmentalists' homes. Corporate America's on board.

Big-box retailers in particular are hitting the accelerator on solar, putting their expansive roofs to work. Manufacturers, grocery stores and a variety of other businesses are tapping the electricity-generating potential of the sun, too.

Commercial-scale solar projects in Maryland didn't even add up to 1.5 megawatts combined in 2008, the Maryland Energy Administration says. Now they top 60 megawatts, more than two-fifths of the state's solar-power capacity, with homes and utility-scale projects accounting for the rest.

Another big increase is coming. As part of its acquisition of Baltimore's Constellation Energy, Exelon Corp. agreed to develop 30 megawatts of solar power in Maryland by 2016.

While businesses are happy to get credit for environmental friendliness, advocates say that's not the only reason — or even the main one — now driving solar.

"I think the most interesting aspect of this story is that you're seeing more and more companies turn to solar as a smart economic investment," said Rhone Resch, CEO of the Solar Energy Industries Association, a national trade group.

Firms partly want to hedge against rising energy prices, Resch said. But plummeting installation costs — thanks to technological advances and efficiency improvements that come with greater scale — are another big reason. The average photovoltaic system costs commercial users about $3.70 a watt to install now, down from more than $7in 2009, SEIA said.

And unlike the early years, companies don't have to shell out up-front. They can pay monthly for the energy with a long-term power purchase agreement and let a solar company or a third party own and maintain the system.

"You're committed, don't get me wrong, but it's basically like paying your monthly electric bill," said Shawn W. Kravetz, president of Esplanade Capital, a Boston investment management firm that focuses on solar and a handful of other sectors. "You're just saving a little bit of money and doing something you can really believe in. It is the financing arrangements that we think have really begun to change the game in this country at the consumer level … but also at the commercial and industrial level."

Walmart is among the companies doing purchase-power deals. It now has about 240 solar installations worldwide, including 10 added atop Maryland stores within the last year.

David Ozment, Walmart's senior director of energy, said solar power has saved the company more than $2 million in energy expenses since late 2007.

"We're demonstrating that we can install solar … truly at or below utility prices," he said.

Federal and state incentives still play a big role in making that happen, though solar advocates say the industry is closer to true "grid parity" than it used to be.

The federal income tax credit for solar is worth 30 percent of the system's cost. And Maryland, which wants 2 percent of retail electricity sales coming from solar power by 2020, requires utilities and retail energy providers to tap solar for a portion of their power.

That's created a revenue stream for solar producers and made projects financially attractive for firms, including those just looking for a good power-purchase deal.

McCormick & Co., which has solar on its Sparks headquarters, its Hunt Valley manufacturing complex and its Belcamp distribution center, said it consistently saves money on electricity bills. But it's not pursuing solar on facilities in states that haven't jump-started a market by setting minimum requirements.

As it is, increased supply has pushed down the value of solar in the marketplace created by the state's retail-sales requirement. Grid operator PJM said the price for 1 megawatt-hour of solar power — traded as a "solar renewable energy certificate" — is about half what it was three years ago.

It's still enough to finance a solar project, thanks to falling installation costs, said Gabriel Phillips, CEO of New York-based GP Renewables & Trading. But "it's pretty skinny," he said.

That drop, and a sharper one in New Jersey, created an opportunity for his company to buy solar installations from disappointed owners and sell power back to them.

"If you own solar, unless you did some sort of unique program that no longer is in place, you are dealing with the [solar certificate] market — and probably not very happy about it," Phillips said.

Plenty of newer adopters are opting to let someone else own from the start. Rockville-based Standard Solar said most of its customers want power purchase agreements that simply lock in their rates for 20 years.

Standard Solar launched in 2004, and it's seen dramatic change since. Its commercial-scale installation numbers have grown at about 30 percent annually for several years.

"The flip side of that is that prices have come down about 30 percent year over year," said Scott Wiater, president of Standard Solar. "From a revenue standpoint, we're up, but not as up as we'd like to be. But it's good for the industry because it's making it more affordable."

The industry has definitely expanded since the early days. California-basedSolarCity entered the Maryland market in 2011 with a dozen employees here. Now it has 102 in the state who work with big firms, smaller companies and homeowners.

"So much of this is about getting in front of more customers," said Lee Keshishian, SolarCity's vice president for the East Coast. "Once people who are interested understand the economics, they want to go with it. It comes down to, do they have the right roof situation and do they have the right financial profile to be eligible."

The family that runs Baltimore-based Cole Roofing launched solar firm Pfister Energy of Baltimore in 2009 because they knew demand would come. Bill Cole, president of both companies, said he's seeing more interest now from firms that were just thinking about it before.

"Our pipeline is much more significant than it was this time a year ago," he said.

Businesses with solar run the gamut locally.

General Motors, for instance, has solar panels on the roof of its White Marsh transmission plant. Solar costs the company about the same amount as conventional power, not less, said facilities manager John W. Peasland. But he likes that the cost is locked in, and "we're buying green energy — we're not just buying off the grid."

There's also solar powering five Kohl's stores in Maryland, plus its Edgewood distribution center. And MOM's Organic Market in Waldorf. And Giant Food's Timonium and Lusby stores. And Leonard Paper Co. in Baltimore, which did solar and a new roof in one fell swoop this fall.

The $2 million solar-plus-storage project at real estate developer Konterra's Laurel headquarters — funded in part with a $250,000 "Game Changer" energy innovation grant from the state — allows the company to tap stored solar power during outages. The unveiling Tuesday drew a bevy of solar industry players and government leaders, all hailing the system.

"I think when we look over our shoulders 15 years from now, this will have become the norm," Gov. Martin O'Malley said afterward.